How to force x-axis labeled gridlines to specific intervals

Sorry for the late response, I've been out of the office. Here is a workaround you can use to make the axis function correctly with short time intervals, until the fix is released.
The Xaml:

<UserControl.Resources>
        <local:TimeTranslator x:Key="translator" />
    </UserControl.Resources>
    
        <Grid x:Name="LayoutRoot" Background="White">
            
        <Grid.RowDefinitions>
            <RowDefinition />
        </Grid.RowDefinitions>

            <ig:XamDataChart Name="xamDataChart1" 
                         VerticalZoomable="True"
                         HorizontalZoomable="True"
                         >
            <ig:XamDataChart.Axes>
                <ig:CategoryDateTimeXAxis x:Name="xAxis" 
                                  ItemsSource="{Binding}" 
                                  DateTimeMemberPath="Date">
                    <ig:CategoryDateTimeXAxis.Label>
                        <DataTemplate>
                            <TextBlock Text="{Binding Item.Date, Converter={StaticResource translator}}" />
                        </DataTemplate>
                    </ig:CategoryDateTimeXAxis.Label>
                </ig:CategoryDateTimeXAxis>
                <ig:NumericYAxis x:Name="yAxis" />
            </ig:XamDataChart.Axes>
            <ig:XamDataChart.Series>
                <ig:LineSeries x:Name="testLine" 
                               ItemsSource="{Binding}" 
                               XAxis="{Binding ElementName=xAxis}"
                               YAxis="{Binding ElementName=yAxis}"
                               ValueMemberPath="Value"
                               />
            </ig:XamDataChart.Series>
        </ig:XamDataChart>

        
    </Grid>

And the code behind:

public partial class MainPage : UserControl
    {
        private DispatcherTimer _timer = new DispatcherTimer();

        public MainPage()
        {
            InitializeComponent();

            DataContext = new TestData();

            _timer.Interval = new TimeSpan(0,0,0,0,250);
            _timer.Tick += timer_Tick;
            _timer.Start();
        }

        void timer_Tick(object sender, EventArgs e)
        {
            ((TestData)DataContext).AddPoint();
        }
    }


    public class TestDataItem
    {
        public DateTime Date { get; set; }
        public double Value { get; set; }
    }

    public class TimeTranslator
        : IValueConverter
    {
        private static DateTime _progStartTime = DateTime.Now;
        public static DateTime Translate(DateTime from)
        {
            return new DateTime(((from - _progStartTime).Ticks * 170000) + _progStartTime.Ticks);
        }
        public static DateTime UnTranslate(DateTime from)
        {
            return new DateTime(((from - _progStartTime).Ticks / 170000) + _progStartTime.Ticks);
        }

        public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
        {
            if ((targetType == typeof(DateTime) || 
                (targetType == typeof(string))) &&
                value is DateTime)
            {
                return UnTranslate((DateTime)value);
            }

            return DateTime.MinValue;
        }

        public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
        {
            throw new NotImplementedException();
        }
    }

    public class TestData
        : ObservableCollection<TestDataItem>
    {

        public TestData()
        {
            for (int i = 0; i < 100; i++)
            {
                AddPoint();
            }
        }

        private static Random rand = new Random();

        int _i;
        double _curr;

        public void AddPoint()
        {
            if (rand.NextDouble() > .5)
            {
                _curr += rand.NextDouble();
            }
            else
            {
                _curr -= rand.NextDouble();
            }

            Add(
                new TestDataItem()
                {
                    Date = TimeTranslator.Translate(DateTime.Now),
                    Value = _curr
                });
            _i++;
        }
    }

-Graham